From left, Dallas Stars' Steve Ott and Loui Eriksson and San Jose Sharks' Logan Couture eye the puck during the first period of an NHL hockey game Thursday, March 31, 2011, in San Jose, Calif. (AP Photo/Ben Margot)— AP

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From left, Dallas Stars' Steve Ott and Loui Eriksson and San Jose Sharks' Logan Couture eye the puck during the first period of an NHL hockey game Thursday, March 31, 2011, in San Jose, Calif. (AP Photo/Ben Margot)
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San Jose Sharks goalie Antti Niemi, right, blocks a shot from Dallas Stars' Jamie Langenbrunner during the first period of an NHL hockey game Thursday, March 31, 2011, in San Jose, Calif. (AP Photo/Ben Margot)— AP

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San Jose Sharks goalie Antti Niemi, right, blocks a shot from Dallas Stars' Jamie Langenbrunner during the first period of an NHL hockey game Thursday, March 31, 2011, in San Jose, Calif. (AP Photo/Ben Margot)
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Dallas Stars' Mike Ribeiro (63) passes the puck away from San Jose Sharks' Dan Boyle (22) during the second period of an NHL hockey game Thursday, March 31, 2011, in San Jose, Calif. (AP Photo/Ben Margot)— AP

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Dallas Stars' Mike Ribeiro (63) passes the puck away from San Jose Sharks' Dan Boyle (22) during the second period of an NHL hockey game Thursday, March 31, 2011, in San Jose, Calif. (AP Photo/Ben Margot)
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SAN JOSE, Calif. 
Antti Niemi made 29 saves for his sixth shutout of the season and Patrick Marleau scored twice to help the San Jose Sharks clinch a playoff spot with a 6-0 victory over the Dallas Stars on Thursday night.

Logan Couture, Dan Boyle, Marc-Edouard Vlasic and Ben Eager also scored for the Sharks, who have won six of seven games to move one point ahead of Detroit for second place in the Western Conference with five games remaining this season.

The Stars lost their fifth straight game as their teetering playoff hopes took another blow. Dallas is three points behind Chicago for the final playoff spot in the West with six games remaining.

Simply making the playoffs is not usually a cause for celebration in San Jose, where the Sharks have been the top in the Western Conference the past two years and one of the NHL's top regular-season teams in recent years.

But considering where the Sharks stood in the middle of January, it is quite notable that they clinched their seventh straight postseason berth with plenty of room to spare. When San Jose dropped its sixth straight game on Jan. 13, falling to Edmonton, the Sharks had the 12th-best record in the Western Conference and were in last place in the Pacific Division.

The Sharks have gone 24-4-4 since that loss in a scintillating stretch they hope they can carry over into the postseason. Niemi has started every game during that run and has been a major reason for the turnaround.

He came up big again in this game, especially with two key saves in the second period when the Sharks took control of the contest. Niemi first stopped a short-handed chance from Jamie Benn early in the period to preserve a 1-0 lead and then helped kill Dallas' third power play of the period with a sprawling stop against Loui Eriksson.

The Sharks followed each of those saves with goals to take a 3-0 lead into the third. With Trevor Daley in the penalty box, Couture did a nice job knocking a puck in the air down with his glove and knocking it in on the backhand to make it 2-0.

Then late in the period, Vlasic sent a point shot through a screen by Devin Setoguchi and past Kari Lehtonen for his third goal of the season to make it 3-0.

Marleau ended Lehtonen's night early in the third when he took a pass from Jamal Mayers, skated past Jeff Woywitka and scored on a wrist shot.

Marleau added his 35th goal and Eager also scored later in the third against Andrew Raycroft as the Sharks posted their most-lopsided shutout victory since also beating Phoenix 6-0 on Nov. 15, 2007.

There was some bad blood between the two teams from their game in Dallas on March 15 when San Jose's Dany Heatley got a two-game suspension for elbowing Steve Ott and Sharks defenseman Niclas Wallin and Eriksson both were injured on hard hits. Ott hit Heatley early in this game and the jawing continued as both players went to the boards.

The Sharks got on board first, set up by a spin-o-rama by Joe Pavelski. He made the move in a one-on-one situation against Woywitka and his backhand was blocked by Lehtonen's pad. But Lehtonen could not cover up the rebound and Boyle beat the Dallas defense to the loose puck and knocked it in for the only goal of the first period.

NOTES: Joe Thornton's two assists gave him 997 career points. ... Marleau had his 50th career multigoal game and also set a franchise record with 12 shots on goal. ... Niemi has 13 career shutouts. ... The Stars have been shutout five times this season.